Common Food Additives: An Experiment Evaluating the Effects of Popular Food Additives

Introduction

Part A of this experiment was conducted in order to determine whether guar gum, cornstarch, or modified food starch was the optimal thickener to add into food. Modified food starch as well as cornstarch thickens foods because of the arrangement of the starch molecules. Modified food starches differ from cornstarch because modified starch provides more stability and solubility than corn starches. Both modified food starch and cornstarch provide energy for the body. While modified and natural starches act as just thickeners, guar gum acted as both a stabilizer and an emulsifier, allowing two things that normally do not mix to combine. Emulsifiers allow hydrophobic substances, which are water-repelling substances, and hydrophilic substances, which are water-loving substances, to blend. Guar gum, unlike the other two food thickeners, does not provide energy when digested.

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In Part B of this experiment, three samples of orange juice were tested using Quantofix test strips to determine the amount of ascorbic acid, or vitamin C, in each sample. Vitamin C is an essential nutrient used for immune functions such as in tissue repair and maintenance (Moore, 2019). The amount of Vitamin C in each sample was compared to the pH of the sample to see if there was a relationship between the two variables. The pH of a substance was measured by immersing a pH strip into the substance and comparing the color of the strip to a color key.

The purpose of Part C was to evaluate if letting a milk mixture sit out in a room with a temperature of 25°C or placing a milk mixture in a water bath with a temperature of 37°C generated the highest amount of useable cheese. Before the experiment started, the milk was pretreated with buttermilk to lower the pH of the milk and denature milk proteins. Rennin, an enzyme, was added to milk. Enzymes are mostly proteins that break down food into nutrients, such as macromolecules, vitamins, and minerals, that the body can easily utilize. 

Methods

In part A, experimenters labeled two vials as modified food starch and corn starch. Then, 0.3g of modified food starch and cornstarch were weighed out using weigh boats and a scale. 10mL of vinegar and 2 mL of vegetable oil were pipetted into the each of the two labeled vials. The 0.3g of cornstarch was then added to the vial labeled for cornstarch. Researchers then shook the vial for 20 seconds and made observations based on how the mixture looked. This process was then repeated for the 0.3g of corn starch. To begin the process of evaluating guar gum, researchers designated a vial for the mixture that would contain 0.2g of guar gum and another vial for the mixture that would contain 2.0g of guar gum. Experimenters then added 10mL of vinegar and 2mL of vegetable oil into each of the two vials. After the guar gum was measured out, the 0.2g of guar gum was added to its corresponding vial and was shaken for 15 seconds. The mixture’s texture, consistency, length to separate, and color were noted. Then, researchers repeated the same process for 2.0g of guar gum.

Researchers began Part B of the experiment by transferring an estimated 15mL of each orange juice sample to three tests tubes using a pipette. A Quantofix Test strip was placed into the test tube containing Sample 1 for ten seconds. After this time, researchers let the strip sit for thirty seconds before a team member compared the color of the test strip to the key provided on the test. This process was then repeated for the other two samples of orange juice with the same team member evaluating the color of the test strip every time. Then, to evaluate the pH of each sample, researchers immersed a pH strip into Sample for two seconds, and then a team member immediately evaluated the pH strip to find the closest color match on the color scale. Researchers completed this process again for Sample 2 and Sample 3.

Before the start of Part C, the milk was treated with buttermilk. Researchers started by marking a beaker 25°C and another 37°C. Then, experimenters transferred 20mL of the milk-buttermilk mixture to each beaker and put eight drops of the enzyme rennin to each beaker. Then, the mixtures were stirred.  The beaker labeled as 37°C was placed in a water bath, while the 25°C beaker remained sitting out. After a fifteen-minute wait, researchers took the 37°C beaker out of the water bath. Then, a team member used the spatula to separate the mixtures into pieces. Researchers poured these mixtures into two separated beakers that were each covered by two sheets of cheesecloth. The liquid portion from each beaker were poured into separate graduated cylinder in order to determine its volume.

Results

Table 1: Observations of Corn Starch and Modified Food Starch

Substance                                Observations                          

With oil and vinegar after shaking

Cornstarch

Thicker and darker than modified corn starch, less bubbles on top, looks like milk, separated in about 8 minutes

Modified Corn Starch

Watery, bubbly on top, clear-white color, stayed together longer than cornstarch mixture

Table 2:Evaluating the Effectiveness of Different Measures of Guar Gum as a Thickening Agent

Guar Gum                   Observations after Shaking                     Observations After 7.5 Minutes

0.2g + oil and vinegar

Watery and thin but thicker than cornstarch and modified cornstarch mixtures, bubbles and separation at top

Thickened up after time, consistency of churned butter, no separation

2g + oil and vinegar

Solidified, no movement of mixture within vial, not completely mixed, slightly yellow color

Texture of slime, slightly jiggly, thickened up after time, not fully mixed, bubbles throughout

Table 3:Evaluated Ascorbic Acid Concentration and pH of Orange Juice Samples

Sample

Concentration of Ascorbic Acid (mg/L)

pH

Kirkland Organic Not from Concentrate (Medium-dark, no pulp, clear)

300

5

Tropicana Bottled from Concentrate (Some pulp, somewhat opaque)

200

4

Minute Maid Frozen from Concentrate (Pulp, very bright)

500

4

Calculations of Amount of Vitamin C in a 4 oz. sample:

4 oz. = 118.29mL = .11829 L

Sample 1: (300mg/1L) x (.11829L) = 35.5 mg per 4 oz. glass

Sample 2: (200 mg/1L) x (.11829L) = 23.7 mg per 4 oz. glass

Sample 3: (500mg/1L) x (.11829L) = 59.1 mg per 4 oz. glass

Table 4:Volume of Original Milk Treatment and Leftover Whey Portion

37°C Beaker

25° C Beaker

Liquid Fraction (whey)

7 mL

17 mL

Original Volume

20 mL

20 mL

Calculations of Percent Usable Cheese:

37°C Beaker: (7mL) / (20mL) = .35mL x 100% = 35% whey

                        100% – 35% = 65% useable cheese

25°C Beaker: (17mL) / (20mL) = .85ml x 100% = 85% whey

                        100% – 85% = 15% useable cheese

Conclusion

            In part A of the experiment, researchers found that guar gum was the most effective thickening agent out of three agents tested. The .2g of guar gum would be the most effective thickening agent in a product that would need to keep its consistency after shipping because the mixture with .2g of guar gum did not separate after a period of time. This is because guar gum acts as an emulsifier, allowing two things that do not usually combine to mix. In the experiment, the mixture with .2g of guar gum did not separate after a period of time unlike the mixtures with corn starch or modified food starch. Although the mixture with 2g of guar gum was the thickest mixture, the mixture was not completely combined. Guar gum should be also be used to create a low-calorie salad dressing. Low-calorie dressings, such as vinaigrettes, typically include oils compared to high-calorie dressings, such as ceaser dressings, which contain milk. In order to include this oils in the dressing, guar gum should be used because of its emulsifying ability. Specifically, the sample with .2g of guar gum should be used over the sample with 2g of guar gum because the 2g mixture was not completely mixed and was extremely thick to the point where it could not be moved. A possible source of error was the transfer of food thickeners, oil, and vinegar to the vials. The weigh boats or pipets could have contained remnants of food thickeners, oil, or vinegar.

            Out of all the samples, Sample 3 (Minute Maid Frozen from Concentrate) had the highest concentration of vitamin C with 500mg per liter. Sample 1 (Kirkland Organic Not from Concentrate Pasteurized) had 300mg of ascorbic acid per liter, while Sample 2 (Tropicana Bottled from Concentrate) had 200mg of ascorbic acid per liter. In regard to the Recommended Dietary Allowance (RDA) for vitamin C, a 4 oz. sample of any of the orange juice tested would not meet the RDA. The RDA for vitamin C for women who are not breastfeeding, pregnant, or smoking is 75mg, and the RDA for vitamin C for men is 90mg (National Institutes for Health Office of Dietary Supplements, 2019) The pH levels of the three samples of orange juice varied slightly. Sample 1 (Kirkland Organic Not from Concentrate Pasteurized) had a pH of 5, while Sample 2 (Tropicana Bottled from Concentrate) and Sample 3 (Minute Maid Frozen from Concentrate) had a pH of 4. Since Vitamin C is ascorbic acid, it should have an acidic pH, which is any pH less than seven. However, the orange juice samples did not show a relationship between pH and amount of Vitamin C, but all three samples had acidic pH levels. The most significant limitation in this part of the experiment involved the pH strips and Quantofix strips that were used to test the samples. Evaluating the color of the strip before or after the indicated time could have affected the color of the pH strip. Since the strips provide a pH or concentration of ascorbic acid off color, it is difficult to get a completely accurate reading.

            In part C of the experiment, researchers found that the milk mixture sitting in the 37°C beaker had the highest percentage of useable cheese. The 37°C beaker produce 65% useable cheese, while the beaker that sat out in room temperature produced 15% useable cheese. Possible sources of error with this part of the experiment involved the temperature of the water bath and room as well as the transfer of materials. The temperature of the water bath was not exactly 37°C and varied a few degrees throughout the duration that the vial was in it. In addition, the temperature of the room in which the experiment took place was assumed to be 25°C. However, the temperature of the room was not evaluated and could have fluctuated. The experiment also included moving the milk mixture to several different containers. In the process of this, it was possible that small amounts of the milk mixture did not make into the final beaker, possibly affecting the amount of whey and the percentage of useable cheese.

References

Moore, M (2019). How vitamin C supports a healthy immune system. Academy of Nutrition and Dietetics. Retrieved from https://www.eatright.org/food/vitamins-and-supplements/types-of-vitamins-and-nutrients/how-vitamin-c-supports-a-healthy-immune-system.

National Institutes of Health Office of Dietary Supplements (2019). Vitamin C. National Institutes of Health Office of Dietary Supplements. Retrieved from https://ods.od.nih.gov/factsheets/VitaminC-Consumer/.